In medicine and various other activities, but especially in orthopedic surgery, for example, various types of screws are driven into, and removed from bone. In such cases, absolute stability of the joined elements is a sine qua non. This factor dictates an absolutely stable engagement of the screwdriver with the fastener being driven. Where, herein, I refer to screws, it is intended to include studs, straight shank machine screws, of any thread form dictated by a particular application and with any desired shape of head, socket-head screws and studs, having in common some portion, e.g. a slot or recess with which the implement is engaged.
When working with bone structure a great deal of strength is often required. In inserting a screw in the terminus of a bone, the operator is often obliged to bear down with considerable force and, since it is frequently impossible to stabilize the body part with any degree of reliability, any shifting of what may be termed the "work piece" is to be avoided. Obviously, dislodgement of the screwdriver can be hazardous and thereby involve risk to the patient. Similar problems arise in those cases where the threads of the fastener are stripped and mismating is to be contended with.
Within the purview of the invention, the portion of the implement adapted to engage the driven element may be constructed to mate with screw heads of the socket type, e.g. the well-known Allen socket head screw, the Phillips type, and numerous others. In some of these cases adapters may be interposed.
Among the objects of the invention are:
1. Stability of the implement in relation to the driven part. PA1 2. Precise placement of the screw in relationship to its hole, allowing rapid starting, driving and extraction of the fastening element.
3. Reliable engagement of the driving tool with the driven part.
4. Easier cleaning and sterilization of instruments and parts thereof.